Structure for mounting rubber printing plates for printing on corrugated and the like board



Apnl 14, 1964 s. KUNETKA 3,128,700

STRUCTURE FOR MOUNTING RUBBER PRINTING PLATES FOR PRINTING ON CORRUGATEDAND THE LIKE BOARD Filed May 11, 1961 2 Sheets-Sheet 1 @E DA INV EN TOR.

KA 3,128,700 PRINTING PLATES FOR ND THE LIKE BOARD 2 Sh Aplll 14, 19645, KU

- STRUCTURE FOR MOUNT N RUB PRINTING ON C0 GATE Filed May 11, 1961sets-Sheet 2 mmmymimimmmmm INVENTOR. ylMa M Ma .QZAMW United StatesPatent STRUCTURE FDR MOUNTKNG RUBBER P'HNG PLATES FUR PRENTING 0NQQRRUGATED AND THE LIKE BOARD Lawrence S. Kunetka, Chicago, lib,assignor to Jefferson State Bank, (Ihicago, ilk, an Eliinois bankingassociation Filed May ill, 19 61, Ser. No. M9579 1 Claim. ((Il. 101-379)This invention relates generally to the typographic arts and moreparticularly, relates to an improved mounting structure for rubberprinting plates of the kind used to print on corrugated paperboard orthe like and ancillary thereto, to provide an improved index device forachieving proper registration of impressions from a rubber printingplate mounted on the said structure.

In the art of printing upon sheet material which is easily crushed andweakened by the printing plate, such as corrugated paper and the like,it has been customary to use rubber printing plates the type face ofwhich has been cut manually or otherwise and to mount the printing plateon a flexible backing member which, in turn, is mechanically fastened onthe circumference of the printing cylinder or roller of the press. Priorto the printing run, it is necessary always to adjust the position ofthe rubber printing plate relative to the backing member in order toachieve proper registration of the imprint on the corrugated board.Accordingly, the rubber printing plate is removably secured on thebacking member by means of a suitable pressure sensitive adhesive havingsufiicient adhesive strength to prevent movement of the printing plateon the backing member during printing and yet which will permit theprinting plate to be removed for adjusting registration, substitutingother printing plates or other reason occasioned by the printingprocess. Also, the printing plates and backing members are subjected toprinting inks and ink solvents and washes during the printing processwhich are penetrating and corrosive in character.

Heretofo-re, several different materials have been used for such backingstructures; however, these have been entirely unsatisfactory for diversereasons. One such material was a flexible, laminated paperboard. Inorder to realize sufficient strength and body for such a backing member,it was considered necessary to use a relatively stiff paper materialhaving the fibers thereof running in one direction for imparting desiredstrength. Further, such sheet material usually available wasapproximately lOOOth of an inch thick and since the desired thickness ofthe backing member normally exceeded 10/ IOOOth of an inch, it wasnecessary to produce a multiple-ply sheet by laminating additionalthicknesses of such material. This paperboard backing member wasrelatively stiff and did not bend readily in a direction transverse tothe length thereof, which would be in a direction parallel to the axisof the printing roller on which it was to be mounted. Because it wasnecessary to remove the printing plate from the backing member forpurposes of registration adjustments, the strong adhesive employedfrequently caused the relatively soft surface of the paper backingmember to peel when the printing plate was stripped off. This not onlymade re-attachement of the printing plate on the paperboard backingmember verydifiicult, but was time consuming and resulted in an unevenmounting surface on the backing member. As a result, when re-aflixingthe rubber printing plate on such an irregular surface, the type face ofthe printing plate was improperly located relative to the printingroller or cylinder and gave rise to unevenness of printing and unevenwear on the type faces of the rubber printing plate. Such irregularitiesin the printing surface of the rubber plate also caused the undesirablecondition of non-uniform pressure being applied to the corrugated boardby the printing plate which, in many instances, resulted in crushed orruptured corrugated board surfaces where the ink was applied from theprinting plate.

Another difiicult problem which arose in connection with the use of sucha paperboard backing member was in connection with the penetratingcharacter of the printing inks and the solvents and Washes used toremove the ink from the rubber type. Because the mounting surface of thebacking member was soft and relatively porous, the inks and solventsreadily penetrated the paperboard member and seeped between the rubberprinting plate and the backing member with resulting undesirableeruptions on the mounting surface and separation of the laminations ofthe multi-ply paperboard member. This adverse condition further wasencouraged by the rather stiff character of the backing member whichlimited the flexibility thereof and facilitated cracking and rupturingof the mounting surface of the backing member transverse to the lengththereof. The resulting fissures in the mounting surface of the backingmember permitted such inks, washes and solvents to be absorbed readilyand easily and thereby limited the extent of which such backing membercould be used repeatedly.

Another type of material which was used for such backing members was afabric material. The fabric backing members also were disadvantageousbecause they were likely to tear readily and could not be made with asufiiciently hard and non-porous mounting surface so that they absorbedprinting inks, washes and solvents commonly used in such printingprocesses. In order to obtain sufiicient body for the backing member, arelatively stiff fabric was used which interfered with realizing an evenprinting or type face when the printing plate was secured on the backingmember. Also, frequent stripping of the printing plate from the backingmember for registration purposes further rendered the surface of thefabric member uneven and irregular with attendant disadvantages.

Another type of material heretofore employed consisted of a sheet ofplastic. Such plastic material was relatively thin in order to obtainthe desired flexibility for the purpose of mounting same on thecircumference of the cylinder but, as a result, the material was tooflexible, did not have sufficient body and readily stretched and buckledespecially after successive uses thereof. Thus, the plastic backingmembers would shrink or stretch, that is, vary in dimension thereof andwould therefore prevent proper registration adjustments to be obtainedand maintained.

Although these various materials have been used for such backingmembers, in no instance was it possible to successfully provide a gridor ruled surface thereon for assisting in adjustments for registration.It was common to provide such grids on the printing rollers for positioning the backing member. However, because imprinting of the grid on thebacking members of previous structures Would be obliterated, Washed orWorn away, they were not employed in connection with any of the backingmembers heretofore used. Consequently, proper adjustment of the printingplate on the backing member was a matter of repeated guess-work andtrial-and-error procedure which further encouraged unevenness andirregularities in the mounting surface of the backing member.

Consequently, it is a major object of the invention to provide astructure of the character described for mounting rubber printing plateswhich will substantially obviate the disadvantages hereinaboveenumerated.

A primary object of the invention is to provide a backing member formounting rubber printing plates having a grid or ruled surface whichwill not be obliterated or washed off during normal use of the printingplate.

Another object of the invention is to provide a backing structure of thecharacter described having a hard m ou nting surface conducive toadhesion of a rubber printing plate thereon by means of a strongpressure sensitive adhesive, said mounting surface being impervious toprinting inks and printing ink solvents and resistant to peeling thereofwhen the printing plate is stripped therefrom repeatedly.

An object of the invention is to provide a backing member for mountingrubber printing plates which comprises, a relatively thin sheet ofpaperboard material formed of a mixture of latex and paper fiber whichis characterized by a significantly higher degree of flexibility thanthat of previous backing sheet materials used for the aforesaid purpose,and a continuous plastic film secured upon a surface of said sheet ofpaperboard which is impervious to the inks, washes and solventsgenerally employed in connection with such rubber printing plates, saidplastic film permitting adherence of the rubber printing plate thereonby means of a strong, pressure sensitive adhesive albeit, permitting theprinting plate to be lifted or stripped from the plastic film repeatedlywithout peeling of the surface of the backing member.

Another important object of the invention is to provide a backingstructure for rubber printing plates comprised of a thin, single-plypaperboard material having a grid or ruled surface formed thereon and afilm of transparent plastic secured upon said surface, said paperboardmaterial being formed of a mixture of latex and paper fibers blendedtogether to realize a backing member having a substantially higherdegree of flexibility than heretofore customary for such backingmembers, and said plastic film forming a very hard surface and beingimpervious and resistant to the inks and solvents customarily used inthe printing process.

An object of the invention is to provide a mounting structure for rubberprinting plates comprising, a relatively thin, flexible, lateximpregnated paperboard member having a hard, plastic mounting surfaceresistant to printing ink and printing ink solvents, and said paperboardmember having a grid provided thereon visible through said plasticsurface.

A further object of the invention is to provide an indexing device forregistration of impressions from rubber printing plates comprising, arubber body having a type face for applying an index impression adaptedto be adhesively secured upon a backing structure for rubber printingplates, said body being readily removable from the backing structureprior to a printing run.

Other objects achieved by the invention will become apparent from theensuing description, among which are significant economies ofmanufacture of the backing structure, resistance of the backingstructure embodying the invention to creasing and cracking, greaterdimen sional stability therefor and desirable strength and body for thebacking structure entirely unexpected and unique considering therelative thin gauge thereof.

A preferred embodiment of the invention has been described in detail inthe specification and illustrated in the accompanying drawings. Minorvariations in structural details thereof may occur to the skilledartisan without departing from the spirit or sacrificing any of theadvantages of the invention.

In the drawings:

FIG. 1 is a fragmentary perspective view of a wooden printing roller andhaving a backing structure mounting a rubber printing plate and anindexing device all embodying the invention secured on the circumferenceof said roller.

FIG. 2 is an enlarged fragmentary plan view of said roller showing thestructure of FIG. 1 secured thereon.

FIG. 3 is a fragmentary sectional view taken along the line 33 of FIG. 1or FIG. 2 and in the direction indicated generally, a portion of a sheetof corrugated paperboard being shown receiving imprints from the rubberprinting plate.

FIG. 4 is a fragmentary sectional view taken through the structure ofFIG. 1 and showing the various layers of materials greatly enlarged.

FIG. 5 is a perspective view of the indexing device installed on thebacking structure embodying the invention.

Referring to the drawings, the reference character 20 represents awooden printing roller or cylinder of a printing press customarily usedfor printing on corrugated paperboard 22 or the like. Ordinarily, thecircumference of the roller 29 is scored or otherwise provided with agrid or ruled surface 24 which is utilized to position a printing plateproperly on the circumference of the roller.

For purposes of describing the invention, certain terms will be used inconnection with the various component parts discussed and illustratedwith the following intended definitions. The term printing plateassembly is defined as the assemblage of components or parts as a unitwhich is secured on the printing roller 20 whereas the terms rubberprinting plate or printing plate is defined as the rubber sheet memberhaving the type face provided thereon. The terms backing member orbacking structure" will be used to define the sheet member on which therubber printing plate or printing plate is adhesively secured. As seenin FIGS. 1 and 2, the printing plate assembly is represented generallyby the reference character 26 and which is secured, as a unit, on theprinting roller 20. The reference character 28 identifies generally therubber printing plate which is adhesively secured on the backing memberor structure identified generally by the reference character 30.

As seen in FIG. 4, the rubber printing plate 28 comprises a sheet 32 ofrubber or rubber-like material the upper surface of which has been cutor otherwise provided with a printing face of type 34 designed totransfer a predetermined imprint of indicia to a surface of thecorrugated paperboard 22. The sheet 32 is affixed on a very thin sheet36 of rubber by means of a coating of pressure sensitive adhesive 33,the opposite or outer surface of the rubber sheet 36 also being coatedwith pressure sensitive adhesive 39 which may be similar to the adhesive38. The printing plate 28 is secured releasably on the backing member 39by means of the coating of adhesive 39. Any suitable pressure sensitiveadhesive may be employed such as a latex cement or glue. The printingplate 28 may be obtained from a supplier already coated with adhesive 39or may be coated by the printer preparatory to using the same.

Backing member 30 includes a specially constructed paperboard sheet 40which is produced from a mixture of latex and paper fibers beaten in aFourdrinier machine, for instance. The sheet 40 is thin and flexible toa degree heretofore not employed or considered feasible for backingsheet materials of this character. One surface 42 of the lateximpregnated paperboard sheet 40 has a transparent or translucent plasticfilm 44 secured thereon which does not reduce the flexibility of thebacking member 30 or materially increase the thickness thereof over thethickness of sheet 40.

The plastic film 44 provides a very hard, non-porous mounting surfacefor the rubber printing plate. Said film 44 may consist of a thin sheetof polyethylene terephthalate, commonly known as Mylar, laminated on thesheet 40 or may be formed by deposition of a vinyl plastic material oversurface 42 in liquid form which subsequently is cured, to seal thesurface 42. Therefore, the term film will be used to connote a coatingof plastic secured on surface 42 of sheet 40 to form a hard, imperviousand non-porous mounting surface for the member 30. The plastic film 44preferably is transparent or translucent.

The backing member 30 also has a grid or ruled surface provided thereonwhich corresponds to the grid or ruled surface 24 on the printing roller20. The grid of the backing member can be provided by suitable lines 46printed or otherwise applied on the surface 42 of sheet 40 which Will becovered by the plastic film 44. Obliteration, erasure or wearing away ofthe grid is positively prevented by film 44. The lines 46 forming thegrid on the backing member will be visible through the normallytransparent or translucent film 44.

The backing member 30 is suitably flexible and thin to permit same to bewound on spools and supplied in rolls to the printer. Although thepaperboard sheet 40 is sufliciently flexible to encourage such windingof the material 30 on reels, it will be apparent that any weakening ofthe sheet 40 which might result during winding will not resultsubsequently in penetration by printing inks and ink solvents of thesheet 40 by reason of the protective covering provided by film 44.

As seen in FIG. 4, the printing plate 28 is removably secured on thefilm 44 by means of the pressure sensitive adhesive 39. Although theprinting plate 28 can be lifited or stripped from the backing member 30repeatedly, no resulting peeling of the backing member will beencountered. Also, since the plastic film 44 prevents printing inks andprinting ink solvents from being absorbed into the sheet material 40,there will be no de-lamination of the backing member encountered such asseparation of the paperboard material 40 and plastic film 44. Further,the plastic film 44 is tough and the sheet member 40 is dimensionallystable and in this manner, the strength and dimensional stability of theentire backing member 30 is maintained over longer periods of time thanheretofore considered probable. Creasing and cracking of the backingmember 30 is entirely absent under normal conditions of use. As aresult, when the printing plate 28 is adhesively aflixed on the backingmember 30, there is no concern that an irregular printing face 34 willbe presented to the corrugated material 22 during printing, as seen inFIG. 3.

It may further be noted from FIGS. 2 and 3 that the printing plateassembly 26 is secured on the roller 20 by mechanical fasteners such asstaples 48 arranged around the perimeter of the backing member 28. Theassembly 26 must be properly positioned relative to the roller 20 so asto avoid high printing portions on the printing face 34. The superiorflexibility of the backing member 30 en ables the assembly 26 to beinstalled on roller 20 in uniform engagement with the circumference ofthe roller as illustrated in FIG. 3.

Referring to FIG. 5, the indexing device embodying the invention isdesignated generally by the reference characted 50. The device 50 iscomprised of a thin sheet 52 of rubber or rubberized material similar tothe sheet 36 seen in FIG. 2. Secured on the sheet 52 is a rubber body 54having a type face 56 cut therein of suitable configuration forregistration purposes, such as a character of indicia having thecruciform configuration illustrated. The underside of the sheet 52 iscoated with a pressure sensitive adhesive, such as adhesive 39, by meansof which the device 50 can be secured removably on the backing member30.

As seen in FIG. 2, the indexing device can be advantageously positionedon the backing member 30 during set-up of a printing press for locatingthe printing plate 23 properly on the backing member 30. Once the pressis set up for a printing run, if desired, the device 50 conveniently canbe removed merely by stripping same from the backing member. However,the device 50 is constructed so that it will not interfere with theprinting by printing plate 28 even if left on the backing member 30because the height thereof above the backing member 30 is substantiallythe same as the height of the printing face 34 above said member 30.

As a precaution against the deleterious effect of printing ink orprinting ink solvent seeping between the printing plate 28 and thebacking member 30, after the printing plate 30 is adhesively secured onthe plate 28, strips 58 of adhesive tape can be used selectively toprevent such seepage. As seen in FIGS. 2 and 3, the strips of tape 58can be sufiiciently wide to cover both the edges of the rubber sheet 32and the thin rubber sheet 36.

It is believed that the invention has been described in sufficientdetail to enable the skilled artisan to understand and practice thesame. The invention has been pointed out distinctly in the appendedclaim in language intended to be liberally and broadly construed.

What it is desired to secure by Letters Patent of the United States is:

A printing plate assembly for printing directly upon corrugatedpaperboard and the like, comprising, a rubber printing plate, a unitary,flexible backing structure adapted to be installed on a printingcylinder and having said printing plate secured on the upper surfacethereof, said printing plate being smaller in both length and Width thansaid backing structure, said backing structure comprising, a flexible,single-ply sheet of latex impregnated paperboard having a very thin,plastic film permanently bonded thereto overlying a face of saidpaperboard sheet and coextensive therewith to provide said surface, saidfilm being harder than said sheet and impervious to conventionalprinting inks and solvents, said assembly being removable from andreplaceable on said cylinder without requiring separating of theprinting plate from the backing structure, and adhesive tape stripssecured overlying the entire edges of said printing plate and adjacentportions of said film for sealing said edges.

References Cited in the file of this patent UNITED STATES PATENTS1,531,554 Harley Mar. 31, 1925 1,607,267 Lublintz et al Nov. 16, 19261,799,217 De Cew Apr. 7, 1931 1,964,236 Welch A June 26, 1934 2,099,154Waters Nov. 16, 1937 2,294,879 Affelder Sept. 8, 1942 2,907,274 TaylorOct. 6, 1959 OTHER REFERENCES Heitt et al.: Silk-Screen ProcessProduction, 1950. (Pages 61 and 62 relied on.)

